strop (n.)

mid-14c., "loop or strap on a harness," probably from Old French estrop, making it the older and more correct form of strap (n.), replaced by it from 16c. Specific sense of "leather strap used for sharpening razors" first recorded 1702. The verb in this sense is from 1841. Related: Stropped; stropping. Distribution of senses between strap and strop is arbitrary.